Then try what xfire said. Burn a copy of Ubuntu to a CD, restart but instead of installing it, use the Try Ubuntu without making any changes to my computer. If you have network on Ubuntu, then the problem is Windows, if not, you may have a problem with your board.

I had a similar problem, bios flashed fine but network ports went dead. Though they were working fine before the flash. For me it was just to reset the bios and well the computer was off/rebooting. I had to go disconnect the cable from the hub/modem (just not the pc). Then powering on the pc, and reattaching the cable.